Short-stretch covered elastic thread



R. c. HALL SHORT STRETCH COVERED ELASTIC THREAD Filed Feb. 28, 192'? f jzyz,

6%} K? ig Patented Aug. 7, 1928.

UNITED STATES 1 1,679,822 PATENT OFFICE.

RAY C. HALL, OF NEEDHAM, MASSACHUSETTS, ASSIGNOR TO FRANK W. GORSE 00., F

7 NEEDHAM HEIGHTS, MASSACHUSETTS,

A CORPORATION OF MASSACHUSETTS.

SHORT-STRETCH COVERED ELASTIC THREAD.

invention relates to elastic covered rubber threads adapted to enter the construcall tttlt tion of a wide variety of knitted and woven fabrics and garments.

Une of the objects of this invention 1s the provision of an elastic covered rubber thread so constructed and arranged that the stretch or elongation of the rubber thread is limited and is held well below the elastic limit or rupture point of the rubber thread.

In the manufacture of the ordinary form of covered rubber thread, some attempt has been made to limit the stretch of the covered rubber thread by greatly stretching the bare rubber thread and holding it in stretched. condition while the covers, usually two 1n number, and each consisting of a plural ty of threads or ends, are wound on tightly with close-pitched convolutions. This method provides a short stretch elastic thread but the thread is always under a relatively heavy tension since the covers hold the thread from contracting and there is nothing to limit the stretch of the rubber thread but the resistance of the rubber thread itself so that 1f the rubber thread is stressed unduly it will rupture.

ber thread and leave a gap in the fabric.

is also difiicult to cover the rubber and stay threads, to entirely conceal the rubber A fabric made of such elastic thread has a relatively short life since the rubber is always under a relatively heavy tension' and is furthermore objectionable since if the rubber thread is severed, as with a needle during the sewing of the fabric, the severed ends will pull away from each other due to the inherent great tension on the rub:

thread, under some conditions.

It is an object of this invention to provide a short, or limited, stretch, low-tension covered elastic thread wherein the stretch of the rubber thread is limited by the characteristic of the covers alone and the manner in which the covers are applied.

A further object of the invention is the provision of a short-stretch, low-tension.

covered elastic thread having such characteristics that it can be made in the usual covering machines, and will lie flat and straight and is free from kinks and loops or a corkscrew eifect.

, A further object is a novel method of covering an elastic rubber thread to provide a short-stretch low-tension covered rubber ,thread.

, A yet further object is generally to im ,prove covered elastic threads and methods of 'inaking them.

Fig. 1 is an enlarged representation of the covered thread embodying this invention with the superimposed covers being successlvely unwrapped to illustrate the character and arrangement of the covers.

Fig. 2 illustrates a section of the elastic rubber thread with the first cover applied thereon.

Fig. 3 is a view similar to Fi 2 but showing the arrangement of the first and. second covers.

Fig. 4 is a view similar to F ig. 2 but showing the application of the third cover over the first two covers.

Fig. 5 is an enlarged view of the thread with the covers partially unwrapped and illustrating the manner in which the covers function to limit the stretch of the clastic rubber thread.

The elastic thread embodying this invention comprises an elastic rubber thread on which are applied a plurality of superimposed spirally-wound textile cover threads 12, 14, 16 and 18. The innermost cover thread 12 is tightly wound onto the elastic rubber 10 in a relatively long-pitched or open spiral as is shown in exaggerated form in Fig. 2. The intermediate cover thread 14 is wound in the. opposite direction over the first cover thread and the rubber thread and the convolutions thereof also have a long pitch, comparable with the pitch of the convolutions of the innermost winding 12,

as lilustrated in Fig. 3. The third layer of cover thread 16 is wound about the two cover threads 13 and 14 oppositely to the cover 14, and has a shorter pitch spiral, or is more closely wound as illusrated in Fig. 4. Each. of the aforesaid covering layers preferably comprises a single thread although for certain purposes the third cover may have more than one thread or end.

The outermost cover 18 is composed of a tion with the under covers,

' layers are wound on the elastic rubber thread in any usual or suitable covering machine and the covers are applied at the same time and in opposite directions so that the rubber thread is held without undue twisting. The elastic rubber' thread 10 is maintained under but a small amount of tension during the covering operation.

The two'inner covers 12 and 14 serve primarily to limit the extent of stretch of the rubber threadalthough the remaining covers also assist in limiting the stretch. As the covered rubber thread is elongated, the pitch of the spirals of the covers 12 and 14 are lengthened causing them to bite into or compress and grip the rubber thread 10 as illustrated in Fig. 5, thereby restricting the stretch of the rubber by compressing it. The length of the covers 12 and 14 when substantially straight is adapted to be less than the extension of the rubber thread before it reaches its elastic limit and consequently further strain on the rubber thread is taken by thecovers which are inextensible and further stretch is prevented. The cover threads 12 and 14 must break before, the rubber thread can be ruptured. The covers 16 and 18 also assist in limiting the stress of the covered rubber fabric by engaging and compressing the rubber thread and thereby offering resistance to its stretch. When the covered thread is unduly stressed, the cover threads usually break one at a time so that the load is thrown upon the successive covers, especially the outer covers 16 and 18 with the rubber thread stretching somewhat when the load is transferred to another cover, thereby considerably relieving the load on the thread.

The cover-elastic thread herein described, in addition to having a limited stretch and an initially low tension, is further characterized by lying flat or straight and is free from kinks or a' cork-screw effect and is similar in appearance to the usual unrestricted-stretch covered elastic thread.

I claim:

1. A short-stretch low-tension covered elastic thread having an elastic rubber thread characterized by being under but little tension when in repose and having a plurality of spirally-wound superimposed covers thereon applied one entirely outside the other, the inner covers having a greater pitch than the outermost cover.

'2. A short-stretch covered elastic thread consisting of an elastic rubber thread having a plurality of cover threads spirally wound thereon, one entirely outside and free from interlocking connection with the other cover threads, at least one of said cover threads characterized by becoming substantially straightened at a point well within the elastic limit of the rubber thread when the covered elastic thread is stretched, whereby to limit the stretch of the rubber thread.

3. A short-stretch covered elastic thread consisting of an elastic rubber thread having a, plurality of covers spirally wound thereon in opposite directions, and any one cover being entirely outside and free from interlocking connection with a lower cover, at least two of said covers cooperating to compress the rubber thread when the covered thread is stretched thereby to limit the amount of stretch, the inner covers being applied in such open spirals as to expose the unextended rubber thread, and the outer cover being applied in such close spiral as to conceal the rubber thread when unextended and also when extended.

4. A covered elastic thread consisting of an elastic rubber thread having two superimposed covers spirally wound in opposite direirtions thereon in a relatively longpitehed open spiral one entirely outside the other and another cover wound upon said first two covers with a shorter-pitched spiral. 5. A covered elastic thread consisting of an elastic rubber thread having two superimposed covers spirally wound in opposite directions thereon in a relatively longpitched open spiral one entirely outside the other, a third cover spirally wound upon said first two covers in a shorter-pit hed open spiral and a fourth multi-ended cover spirally wound upon said rubber and over the aforesaid covers, the winding-pitch of certain of said covers being different.

6. A covered elastic thread consisting of an elastic rubber thread having an outside cover and a plurality of inner covers successively-operable to limit the stretch of the thread, said inner covers characterized b permitting the rubber thread to stretc i somewhat upon the breaking of one of said covers whereby to apply the tension upon another of said covers.

7. A restricted-stretch covered elastic thread consisting of an elastic thread having a plurality of independent covers consisting of inelastic threads wound in superimposed and alternately reversed order in opposite directions one entirely outside the other on said elastic thread, said covers characterized by having convolutions of digering pitches, and differing numbers of en s.

In testimony whereof, I have signed my name to this specification.

RAY C. HALL. 

